Field of the Invention
The present invention relates to an organic light emitting device. More particularly, the present invention relates to an organic light emitting device which is manufactured using a solution process.
Discussion of the Related Art
Organic light emitting devices are devices which have a structure, where an emission layer is formed between a cathode injecting an electron and an anode injecting a hole. When the electron generated from the cathode and the hole generated from the anode are injected into the emission layer, the injected electron and hole are combined to generate an exciton, and the exciton is shifted from an excited state to a ground state to emit light.
A related art organic light emitting device will be described with reference FIG. 1.
FIG. 1 is a schematic cross-sectional view of a related art organic light emitting device.
As seen in FIG. 1, the related art organic light emitting device includes an anode, a hole injecting layer (HIL), a hole transporting layer (HTL), an emission layer (EML), an electron transporting layer (ETL), an electron injecting layer (EIL), and a cathode.
Organic layers, such as the HIL, the HTL, the EML, the ETL, and the EIL which are disposed between the anode and the cathode, are formed through a vacuum deposition process in a vacuum chamber. However, since the vacuum deposition process is used, high-cost vacuum deposition equipment is needed, and for this reason, the manufacturing cost increases. Particularly, when a size of an organic light emitting device increases, a size of the vacuum deposition equipment further increases. For this reason, productivity is lowered in mass production.
Therefore, ongoing research on a method of forming the organic layers through a solution process is being performed. As a result, a method of forming the HIL, the HTL, and the EML through the solution process has been proposed. However, a method of forming the ETL disposed on the EML through the solution process is not yet developed. This is because when the ETL is formed by the solution process, a surface of the EML is damaged by a solvent contained in a solution which is used to form the EML. To date, therefore, only the HIL, the HTL, and the EML are formed by the solution process, and the ETL and the EIL are formed by the vacuum deposition process. In this case, productivity is more enhanced than a case where all the organic layers are formed by the vacuum deposition process. However, productivity is still lowered in a case of manufacturing a large-size organic light emitting device.